Revise HIR lowering comment

Author: edward-shen

Diff for: compiler/rustc_mir/src/borrow_check/diagnostics/region_name.rs

@@ -634,8 +634,8 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
                     | GenericArgKind::Const(_),
                     _,
                 ) => {
-                    // HIR lowering is insufficient in erroneous programs, so
-                    // we need to use delay_span_bug here. See #82126.
+                    // HIR lowering sometimes doesn't catch this in erroneous
+                    // programs, so we need to use delay_span_bug here. See #82126.
                     self.infcx.tcx.sess.delay_span_bug(
                         hir_arg.span(),
                         &format!("unmatched subst and hir arg: found {:?} vs {:?}", kind, hir_arg),